Isomerization of aldoses to ketoses is an essential step in carbohydrate valorization routes in biorefineries to produce a wide variety of bioproducts. In this work, selective isomerization of aldoses into ketoses was investigated using different commercial Brønsted basic anion resins at low temperature conditions. Weak and strong basic resins were tested under different reaction conditions. Amberlite IRA-900 and Amberlyst A-26 (strong resins) and Amberlite IRA-67 and Amberlyst A-21 (weak resins) were tested to assess their catalytic properties. Strong basic resins provided high yields of fructose. IRA-900 was also tested in the isomerization of different sugar monosaccharides conventionally present in lignocellulosic biomass (xylose, arabinose, galactose, glucose and mannose) aiming to explore the performance of this material in hemicellulose-derived sugar mixtures. Very promising performance was observed for IRA-900, yielding fructose selectivity higher than 75% and fructose yield of 27% in the isomerization reaction. Notably, basic anionic resins were not suitable for reuse in different reaction cycles, although the use of organic cosolvents, specifically ethanol, improved the reusability of the tested resins.

Molecular modelling studies were carried out at the DFT level of the adsorption of propane and propene on Ag surfaces as a model of the interaction of light hydrocarbons with Ag/ZrO₂ catalysts for catalytic combustion reactions. It was found that the most stable mode of adsorption of propene through its π system on Ag atom has energies consistent with chemisorption and generates an elongation of the C1=C2 bond, which would explain the increase in the activity of the catalysts as a function of its metallic charge. The results obtained from the DFT calculations explain the different types of interactions between propene and propane with the metallic surface. The propene is chemisorbed on the Ag surface, distorting its bonds and generating its activation. This would imply that a higher metallic charge in the catalyst would increase the number of active sites in which this activation occurs, generating a higher activity. In addition, with the addition of O, the binding energy between the propene and the metal surface increased. On the other hand, the presence of a metallic surface is not enough for the activation of the propane molecule. This would explain why, by increasing the amount of metal in the catalyst, the activity for the combustion of propane is practically not affected.

La innovación en tecnologías orientadas a la eliminación de contaminantes emergentes es de suma importancia debido a que la presencia de estos compuestos en cuerpos de aguas residuales y superficiales representa un desafío ambiental. La fotocatálisis heterogénea usando TiO2 se presenta como una tecnología con potencialidad en esta área y desafíos por resolver. En este trabajo se propone modificar el TiO2 con paladio para explorar la degradación de fármacos en solución acuosa. Se sintetizaron materiales de TiO2 con 0,1 at. % nominal Pd por sol-gel variando condiciones de síntesis (solvente, T envejecimiento, atmósfera de calcinación). Los materiales se caracterizaron por XRD, TEM, ATR-IR, DRS y XPS para determinar sus principales propiedades fisicoquímicas. Los materiales de TiO2 modificados con Pd alcanzaron mayores porcentajes de degradación de fenol en comparación con TiO2, tanto bajo irradiación UV-A como visible, usando un reactor Rayonet. El fotocatalizador más activo se evaluó para la degradación de cinco contaminantes emergentes en solución acuosa. Se logró degradar diclofenaco (95%), ibuprofeno (77%), cafeína (60%), atenolol (57%) y carbamazepina (22%), luego de 4 h bajo irradiación con luz visible.

This work presents the results of the acetalization reaction between furfural and polyols (ethylene glycol or glycerol), employing an ionic liquid, 1-(4-sulfonic acid) butyl-3-methylimidazolium hydrogen sulfate, [C4SO3Hmim][HSO4], as a catalyst. Two series of catalysts were prepared and characterized. These catalysts were supported on silica gel 60 and on SBA-15 mesoporous silica, with variable IL loading (10 - 50 wt%). All of them showed good activity in the formation of the desired cyclic ethers, 2-(furan-2-yl)-1,3-dioxolane and the cis-trans (2-(furan-2-yl)-1,3-dioxolan-4-yl) methanol and cis-trans (2-(furan-2-yl)-1,3-dioxan-5-ol isomers. Furthermore, the activity exhibited by some of these catalysts surpassed that of the unsupported IL. The catalyst SBAIL30 was the most active, with a cyclic acetal yield of 51%. This particular sample is characterized by its elevated number of strong acid sites, a property that is supported by the results of the XPS analysis. These strong acid sites are believed to be derived from the presence of sulfonic groups within the IL. The use of heterogeneous catalysts had a significantly impact on the stereochemistry of the reaction. While the 6-membered ring is the most thermodynamically stable product, SILx and SBAILx catalysts were found to favor the formation of the 5-membered ring in a higher proportion than that found in the reaction performed in the absence of catalyst.